Client Script g_form.setReadOnly() not working.

[JavaScriptMaest]

g_form.setReadOnly() method not working when I run it through Client Script, but it works when I run the same on the JavaScript Executor(Ctrl + Alt + Shift + J), is there a way to debug and know what is stopping my Client Script code to not work on setting the field read only. 

The Client Script is:

[Derek Behunin]

Can you share your client script so we have a better idea of what your running looks like?
Also when is your client script running?

[JavaScriptMaest]

[Derek Behunin]

I would test all your scratchpad variables and make sure they're holding all the correct/expected data. If they are try this loop in place of fieldsArray.forEach

for (x in fieldsArray){
    g_form.setReadOnly(x, true);
}

[JavaScriptMaest]

Yes, I have double checked that all of the scratchpad variables are holding the correct values. The for... in loop is unsuitable and not suggested to loop over an array as it is best used to enumerate over object properties, when you use for...in it returns the array index(number).